System for electric valve translating apparatus



Oct. 27, 1942. Y. TODA 2,300,269

v SYSTEM FOR ELECTRLC VALVE TRANSLATING APPARATUS Filed May 24, 1940Inventof Yoshiaki Toda,

' 6 AM by l mtorhey Patented Oct. 27, 1942 SYSTEM FOR ELECTRIC VALVETRANSLAT- ING APPARATUS Yoshiaki Toda, Tokyo, Japan, assignor to GeneralElectric Company, a corporation of New York Application May 24, 1940,Serial No. 336,995 In Japan September 27, 1939 9 Claims.

My invention relates to electric valve translating apparatus and moreparticularly to a protective or control system for electric valveapparatus of the type employing an ionizable medium, such as a gas or avapor.

It is frequently desirable in the control of electric valve translatingapparatus to provide means for reducing the current conducted by theelectric valve means in the event of an abnormal operating conditionsuch as arc-back. In accordance with the teachings of my inventiondescribed hereinafter, I provide a new and improved control system forelectric valves utilizing apparatus for suppressing the currentconducted during an arc-back condition and for restoring the rectifiersto normal operation.

It is an object of my invention to provide a new and improved electricvalve translating systerm.

It is another object of my invention to provide a new and improvedcontrol and protective system. for electric valve translating apparatus.

It is a further object of my invention to provide a new and improvedarc-back suppression system for electric valve rectifiers wherein theelectric valves are rendered non-conductive upon the occurrence of anarc-back and wherein the electric valves are gradually restored to thenormal operating condition.

Briefly stated, in the illustrated embodiment of my invention I providean improved system for reducing the current conducted by electric valvemeans upon the occurrence of an irregular or abnormal operatingcondition, such as arcback. Upon the occurrence of an overload conditionor upon the occurrence of an arc-back, the normal grid excitation forthe electric valve means is removed and the negative voltage isimpressed on the grids to supp the arc and reduce the current conductedby the electric valve means. The grid excitation is automaticallyre-applied but is modified in a manner to effeet a gradual increase ofthe current conducted by the electric valve means, thereby restoring thesystem to its normal operation.

For a better understanding of my invention, reference may be had to thefollowing description taken in connection with the accompanying drawing,and its scope will be pointed out in the appended claims. The singlefigure of the accompanying drawing diagrammatically illustrates anembodiment of my invention as applied to a three phase rectifier.

Referring now to the single figure of the drawing, my invention is thereillustrated as applied to an electric valve rectifying system forenergizing a direct current load circuit I from a polyphase alternatingcurrent supply circuit 2 through electric translating apparatuscomprising a transformer 3 having primary windings 4 and secondarywindings 5, and includes an electric valve means 6 preferably of thetype employing an ionizable medium such as a gas or a vapor and havingan anode l, a cathode 8 and at least one control member or grid 9. Itwill be understood, of course, that the electric valve means may be ofthe type employing a plurality of anodes I each having an associatedcontrol grid 9 and utilizing a single associated cathode such as thatshown.

I provide an excitation circuit ID for impressing on the control grids 9periodic voltages to render the associated arc discharge paths of theelectric valve means 6 conductive in a predetermined order or sequence.The excitation circuit l0 may comprise a transformer ll having primarywindings l2 and secondary windings I3 and includes a suitable phaseshifting device, such as a rotary phase shifter I4, preferably having adistributed stator winding I 5 and a secondary winding l6 mounted upon arotatable structure to produce the desired shift or change in phase ofthe voltages impressed on the control grids 9 relative to the respectiveanode-cathode voltages. The rotary phase shifter I4 is also providedwith a member I! which rotates in accordance with the angular positionof the rotatable structure of the phase shifter and includes stopmembers I8 and I9 which engage the member I! when the rotating structureof the phase shifting structure assumes certain limiting positions. Forexample, the stop It! establishes the full-on or maximum output voltageof the electric valve means 6 and the stop I!) establishes the point orposition of zero output voltage or zero power output of the electricvalve means '6. The output or secondary voltages of the rotary phaseshifter I4 are preferably converted into alternating or periodicvoltages of peaked wave form by suitable apparatus, such as a saturablepeaking transformer 20 comprising primary windings 2| and a plurality ofsecondary windings 22 having an electrical neutral connection 23. Toprovide a suitable source of negative unidirectional biasing potentialsufficient in itself, when acting alone, to suppress the arc dischargeof the electric valve means 6 under arc-back conditions, I employ asuitable means such as a battery 24, which may be connected between thecathode 8 and the neutral connection 23 of secondary windings 22. Ofcourse, the voltage furnished by battery 24 cooperates with the voltagesof peaked wave form produced by secondary windings 22 of transformer torender the arc discharge paths of the electric valve means 6 conductivein a predetermined order. The phase position of the voltages of peakedwave form are controlled by the angular position of the rotating memberof the rotary phase shifting device l4.

The excitation circuit III also includes switching means, such as a pairof switching means 25 and 26, which control the energization of therotary phase shifting device l4. The switching means 25 includes asuitable actuating means, such as a closing and holding coil 21, holdingcontacts 28 and means, such as auxiliary contacts 29, for initiating theenergization of the closing and holding coil 30 of the switching means26. The switching means 25 is also provided with a suitable pair ofcontacts 3| which are effective to control the energization of thepositioning means for the rotary phase shifting device M. Thispositioning means is described in detail hereinafter. The switchingmeans 25 is biased by a suitable means, such as a spring 32, to be movedto the open circuit position upon the deenergization of the closing coilor holding coil 21.

Switching means 26 is also provided with a set of auxiliary contacts 33which complete a circuit for the energization of the closing coil 21 ofthe switching means 25 when the switching means 26 is in the opencircuit position, thereby providing a circuit for initiating the closureof switch 25 when switch 26 is in the open circuit 1 position. Switchingmeans 26 is also provided with a further set of auxiliary contacts 34which operate to control the positioning means described hereinafter.Closing coils 21 and 3|] of switching means 25 and 26, respectively, maybe energized from a suitable source of current, such as a, directcurrent circuit 35, and a control switch 36 may be connected in seriesrelation with contacts 33 to initiate or discontinue operation of thesystem.

Switching means 26 is connected between the secondary windings |3 oftransformer I I and the stator winding |5 of rotary phase shiftingdevice H in a manner to change the phase rotation of the output voltageof the phase shifting device l4. In this manner, when switching means 26is closed, upon the occurrence of an abnormal condition, the outputvoltage of the phase shifting device l4 may be arranged to impress aninstantaneously negative voltage on certain grids of electric valvemeans 6. In this manner, the alternating voltages of the phase shifter Mare additionally shifted in phase during the protective operation.

As an agency for effecting selective operation of switching means 25 and26 in response to the angular position of the rotary phase shifter 4, Iprovide a suitable controlling means 31. Controlling means 31 may bemechanically coupled to the rotating structure of the phase shiftingdevice l4 and may comprise a drum contactor 38 having stationarycontacts 39 and 40 and associated movable contacts 4| and 42,respectively. Contact 4| is dimensioned so that it engages contacts 39only when the rotary phase shifting device 36 is in that positioncorresponding to zero output voltage or reduced power output of theelectric valve means 6, that is, contact 4| engages contacts 39 onlywhen the member engages stop I9. The contact 42 is furthermoreproportioned so that it engages or completes the circuit throughcontacts 40 at all times excepting when the member engages contacts 19.In this manner, the closing coil or the holding coil 30 of switchingmeans 26 is energized when the switching means 25 is in the open circuitposition so long as the rotary phase shifter I4 is not moved to theextreme retarded position where the member engages stop l9. When thatposition is reached, the energizing coil for coil 30 is open and thecircuit for energizing coil 21 is completed through a circuit includingcontacts 39 and 4|.

I provide a positioning means 43 for controlling the position of therotary phase shifter l4 and hence the phase of the voltages impressed onthe grids 9. This positioning means may comprise a suitable motor, suchas a direct current motor 44, having an armature 45 and a pair of fieldwindings 46 and 41 which are selectively energized to control thedirection of rotation of the armature 45. I also provide a pair ofadjustable resistances 48 and 49 which determine and permit independentadjustment of the rates of forward and reverse rotation of the armature45 and hence permit independent adjustment of the rate of advancementand retardation of the periodic voltages impressed on the grids 9. Thecircuits for field windings 46 and 41 are energized from the directcurrent circuit 35.

I provide a suitable means, such as an overload relay 50, responsive toa predetermined operating condition such as an abnormal operatingcondition of the electric translating circuit to initiate the operationof the protective system. The relay 56 may comprise an actuating coil 5|energized in response to the anode-cathode current of the electric valvemeans 6. A suitable current transformer 52 may be employed for thispurpose. Relay 56 also comprises a pair of contacts 53 which shunt theclosing coil 21 of switching means 25 and hence initiate the operationof the system. Relay 56 also includes contacts 54 which serve tocomplete a circuit for the proper control of the positioning means 43upon the occurrence of the abnormal condition.

Resistance 34 is connected in circuit with the contacts 54 of relay 5!)and is an element in the circuit which energizes field coil 41 of motor44 when auxiliary contacts 34 of switching means 26 are closed.Resistance 34 is also connected to the neutral connection 23 ofsecondary windings 22 to provide an additional negative biasing voltagewhen contacts 54 of relay 5!] and contacts 34 of switching means 26 areclosed.

The operation of the embodiment of my invention shown in the singlefigure of the drawing will be explained by considering the system whenit is operating as a rectifier to transmit unidirectional current to theload circuit I from supply circuit 2. The three are paths of theelectric valve means 6, of course, conduct current in order, each anodetransmitting the load current for electrical degrees during each cycleof voltage of circuit 2. The magnitude of the voltage impressed on thedirect current circuit is, of course, determined by the phase relationbetween the voltages impressed on the grids 9 and the anode-cathodevoltages. The load voltage is maximum as the grid voltages are broughtmore nearly into phase coincidence with the anode-cathode voltages and,conversely, the load decreases as the grid voltages are retarded inphase. The periodic voltages of peaked wave form produced by the peakingtransformer 50,

under normal conditions, are of suflicient magnitude to overcome theeffect of the negative biasing voltage produced by battery 24. Thesystem operates to suppress arc-backs upon the occurrence thereof andalso operates to reduce the load transmitted by the electric valve means6 and to effect a gradual re-application of load thereto.

During normal operating conditions, the phase shifting device I4 isenergized through transformer H, the switching means 25 being maintainedin the closed circuit position by the energization of the closing coil21 through a circuit including the positive terminal of circuit 35, coil21, holding contacts 28, contacts 33 of switching means 26, switch 36,and the negative terminal of the circuit 35. Of course, by openingswitch 36 this circuit may be interrupted to deenergize coil 21 andpermit'the movement of switching means 25 to the open circuit positionthereby rendering valve means 6 non-conducting. In like manner, byclosing switch 36 the system may be placed in operation.

If it be assumed that the system is subjected to an abnormal operatingcondition, such as an arc-back, the increase in current in theassociated alternating circuit will effect operation of relay 50. Uponoperation of relay 50, contacts 53 are closed, thereby shunting holdingor closing coil 21 of switching means 25 and effecting deenergizationthereof and permitting movement of the switching means 25 to the opencircuit position, removing for a predetermined time the energizingvoltage for the excitation circuit I8. Upon removal of the periodicvoltage of peaked wave form from the grids 9, the negative biasingpotential furnished by battery 24 is suflicient to suppress the arewithin electric valve means 8 and thereby render the electric valvemeans nonconductive and consequently correct the disturbance.

After switching means 25 is permitted to move to the open circuitposition, closing and holding coil 3|] of switching means 26 isenergized through a circuit including the positive terminal of circuit35, coil 30, contacts 40 and 42 of the drum 38, contacts 29 which areclosed since switching means 25 is in the open circuit position, and thenegative terminal of circuit 35. Upon the energization of coil 30,switching means 26 is moved to the closed circuit position. Upon closureof switching means 26, auxiliary contacts 34 are also closed effectingenergization of the positioning means 43 in a manner to retard therotary phase shifter M to a position corresponding to the zero voltageposition, that is, to that position where member I! engages stop l9.Field winding 41 of motor 44 is energized to retard phase shiftingdevice |4 through the following circuit: the positive terminal ofcircuit 35, contacts 54 of relay resistance 34', auxiliary contacts 34of switching means 26, resistance 49, winding 41 and the negativeterminal of circuit 35. This position of the rotary phase shiftingdevice l4 corresponds to zero voltage output of the electric valve means6. During the time when contacts 54 of relay 50 are closed and contacts34 of switching means 26 are closed, an additional negative bias voltageis impressed on grids 9 by means of resistance 34'. This bias voltage isproduced so long as contacts 54 and 34 are closed. Resistance 34 isenergized through a circuit including the positive terminal of source35, contacts 54 of relay 50, resistance 34', contacts 34, resistance 49,field winding 41,

and the negative terminal of source 35. As soon as either contacts 54 or34 open, the bias voltage produced by resistance 34 disappears. Ofcourse, it is desirable to provide this additional bias voltage duringthe operation in which phase shifter 4 is retarded. After switchingmeans 26 opens, phase shifter I4 is slowly advanced and it is desirabletoremove thebias voltage so that the current conducted by electric valvemeans 6 may be gradually increased. At this position of the rotary'phaseshifter I4, the contacts 40 and 42 of the drum contactor 38 are not inengagement and contacts 39 and 4| are engaged. Contacts 40 and 42 in theopen circuit position deenergize the holding and closing coil 38 ofswitching means 26, permitting movement of this switching means to theopen circuit position. Closure of contacts 39 and 4| effectsenergization of the closing coil 21 of switching means 25, movingswitching means 25 to the closed circuit position. The circuit forenergization of closing coil 21 at this stage in the operation of thesystem includes the positive terminal of circuit 35, contacts 39 and 4|,contacts 33, switch 36 and the negative terminal of circuit 35.Accordingly, the phase shifting device [4 is rotated by means of motor44 to advance gradually the phase of the periodic voltages impressed ongrids 9 from the zero voltage position to the normal or full voltageposition. The rate at which the periodic voltages are advanced in phaseis determiend, of course, by the adjustment of resistance 48. Thecircuit for effecting energization of the motor 44 to advance the phaseof the periodic voltages is as follows: the positive terminal of circuit35, contacts 3| of switching means 25, resistance 48, field winding 34,and the negative terminal of circuit 35. The phase shifting device I4 isadvanced gradually until the member engages stop I8, at which time theoutput voltage of the electric valve means 6 has been increased to itsnominal or rated value. The system is then reset to the initialcondition to permit reduction of loadand arc suppression in the event ofanother arc-back condition.

.From the above-described operation of the system, it will be understoodthat negative voltages are impressed on the grids 9 almostinstantaneously upon the occurrence of an arcback condition, and thatthe load is applied gradually to the electric valve means 6.Furthermore, the movable member of the rotary phase shifting device I4is retarded very rapidly as compared with the rate of advancement. Thisselective adjustment or control of the relative rates of retardation andadvancement is obtainable by means of resistances 49 and 4B,respectively. The motor 44 is made to retard the rotary phase shiftingdevice |4 Very rapidly and is controlled to advance the device l4slowly.

While I have shown and described my invention as applied to a particularsystem of connections and as embodying various devices diagrammaticallyshown, it will be obvious to those skilled in the art that changes andmodifications may be made without departing from my invention, and I,therefore, aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure, by Letters Patent of theUnited States is:

1. In combination, an alternating current circuit, a direct currentcircuit, electric translating apparatus connected between said circuitsand comprising electric valve means having at'least one control memberfor controlling the current conducted thereby, an excitation circuitcomprising phase shifting means for impressing on said control member aperiodic voltage variable in phase relative to the voltage of saidalternating current circuit, a source of negative unidirectional biasingpotential sufficient to render said electric valve means non-conductive,means responsive to a predetermined electrical condition of one of thefirst mentioned circuits for removing said periodic voltage therebypermitting said biasing potential to render said electric valve meansnon-conductive, control means for said phase shifting means forretarding and advanc ing the phase of said periodic voltage, andelectrical means for independently adjusting the relative rates ofretardation and advancement of said periodic voltage.

2. In combination, an alternating current circuit, a direct currentcircuit, electric translating apparatus connected between said circuitsand comprising electric valve means having at least one control memberfor controlling the current conducted thereby, an excitation circuitcomprising phase shifting means for impressing a periodic voltage onsaid control member, positioning means for said phase shifting means,means for impressing a biasing potential on said grid, means forremoving said periodic voltage from said control member so that saidbiasing potential renders said electric valve means non-conducting,means for energizing said positioning means to retard in phase saidperiodic voltage while it is ineffective to control said electric valvemeans and for subsequently applying said periodic voltage to saidcontrol member and for advancing the phase of said periodic voltagerelative to the voltage of said alternating current circuit, andelectrical means for independently adjusting the relative rates ofretardation and advancement of said periodic voltage.-

3. In combination, an alternating current circuit, a direct currentcircuit, electric translating apparatus connected between said circuitsand comprising electric valve means having at least one control memberfor controlling the current conducted thereby, a source of negativeunidirectional biasing potential suflicient in itself to render saidelectric valve means non-conductive, means responsive to an operatingcondition of said electric valve means for controlling the phase of saidperiodic voltage to permit said negative biasing potential to rendersaid electric valve means non-conductive, and means for controlling saidperiodic voltage to increase gradually the current conducted by saidelectric valve means.

4. In combination, an alternating current circuit, a direct currentcircuit, electric translating apparatus connected between said circuitsand comprising electric valve means having at least one control memberfor controlling the current conducted thereby, an excitation circuit forimpressing a periodic control voltage on said control member andcomprising switching means for connecting said excitation circuit tosaid alternating current circuit and including a rotary phase shiftingdevice for controlling the phase of said periodic voltage, positioningmeans for operating said rotary phase shifting device, and meansresponsive to a predetermined operating condition of said electric valvemeans for moving said switching means to the open circuit position,energizing said positioning means to decrease the current conducted bysaid electric valve means and for subsequently closing said switchingmeans and operating said positioning means to increase gradually thecurrent conducted by said electric valve means.

5. In combination, an alternating current circuit, a load circuit,electric valve translating apparatus connected between said circuits fortransmitting power therebetween and comprising at least one controlmember for controlling the current conducted thereby, an excitationcircuit energized from said alternating current circuit and comprising arotary phase shifter for impressing on said control member a periodicvoltage, a source of negative biasing potential and positioning meansfor said phase shifter to control the phase of said periodic voltage, apair of switching means interposed between said excitation circuit andsaid alternating current circuit, interlocking means connected betweensaid pair of switching means to prevent simultaneous closure of saidswitching means, means responsive to a predetermined electricalcondition of said translating apparatus for opening one of saidswitching means, means for energizing said positioning means to retardsaid rotary phase shifting device, and means responsive to the operationof said pair of switching devices for operating said rotary phaseshifting device to advance the phase of said periodic voltage.

6. In combination, an alternating current circuit, a direct currentcircuit, electric translating apparatus connected between said circuitsand comprising an electric valve means having at least one controlmember for controlling the current conducted thereby, a source ofnegative unidirectional biasing potential, an excitation circuit forimpressing a periodic voltage on said control member sufficient inmagnitude to overcome the effect of said biasing potential and includinga rotary phase shifting device for controlling the phase of saidperiodic voltage, positioning means for operating said rotary phaseshifting device, means responsive to a predetermined operating conditionof said electric valve means for moving said switching means to the opencircuit position thereby removing said periodic voltage from saidcontrol member and rendering effective said negative unidirectionalbiasing potential to interrupt the current transmitted by said electricvalve means, and means for subsequently closing said switching means andoperating said positioning means to increase gradually the currentconducted by said electric valve means.

7. In combination, an alternating current circuit, a direct currentcircuit, electric translating apparatus connected between said circuitsand comprising electric valve means having at least one control memberfor controlling the current conducted thereby, a source of negativeunidirectional biasing potential sufficient in itself to render saidelectric valve means non-conductive, an excitation circuit forimpressing a periodic control voltage on said control member and of amagnitude suflicient to overcome the effect of said biasing potential, apair of switching means for connecting said excitation circuit to saidalternating current circuit and including a rotary phase shifting devicefor controlling the phase of said periodic voltage, actuating means forsaid pair of switching means, interlocking means con.- nected betweensaid pair of switching means for effecting closure of one of saidswitching means upon the opening of the other switching means,positioning means for said rotary phase shifting device, meansresponsive to a predetermined operating condition of said electric valvemeans for energizing the positioning means for said phase shiftingdevice to open one of said switching means and retard the phase of saidperiodic voltage, and means responsive to said one switching means toclose the other switching means and to open subsequently said otherswitching means and to close said one switching means and lastlyeffecting a gradual advancement in the phase of said periodic voltage.

8. In combination, an alternating current circuit, a direct currentcircuit, electric translating apparatus connected between said circuitsand comprising electric valve means having at least one control memberfor controlling the current conducted thereby, a source of polyphasealternating current, an excitation circuit comprising phase shiftingmeans for impressing on said control member a periodic voltage variablein phase relative to the voltage of said alternating current circuit,said phase shifting means being of the rotary type having a polyphasestator winding and a polyphase output winding, switching means forconnecting said source to said stator winding to produce the samedirection of phase rotation of the output voltages of said statorwinding as the phase rotation of said alternating current circuit, asecond switching means for connecting said source to said stator Windingto produce a different order of phase rotation of the voltages of theoutput winding relative to the voltages of said alternating currentcircuit, means for controlling the first mentioned switching means tomaintain that switching means closed during normal operation of saidelectric valve means, and means responsive to a predetermined operatingcondition of said electric valve means to open the first mentionedswitching means and to close said second switching means for apredetermined interval of time.

9. In combination, a polyphase alternating current circuit, a directcurrent circuit, electric translating apparatus connected between saidcircuits and comprising electric valve means having a plurality ofanodes and a plurality of associated control members for controlling thecurrent conducted thereby, a source of negative unidirectional biasingpotential suificient in itself to render said electric Valve meansnon-conductive, a

source of polyphase alternating current, an eXcitation circuit includinga polyphase rotary phase shifting device for impressing on said controlmembers periodic voltages adjustable in phase with respect to thevoltages of said alternating current circuit, switching means connectedbetween said source and said phase shifting device so that said phaseshifting device supplies to said control members voltages having thesame order of phase rotation as the voltages of said alternating currentcircuit, a second switching means for energizing said phase shiftingdevice from said source in a manner so that said phase shifting devicesupplies voltages having a diiferent order of phase rotation relative tothe Voltage of said alternating current circuit, means for maintainingthe first mentioned switching means in the closed circuit positionduring normal operation, means for maintaining said second switchingmeans in the open circuit position during normal operation. meansresponsive to a predetermined electrical condition for opening the firstmentioned switching means and thereby permitting said negative biasingpotential to render said electric valve means non-conductive, means forclosing said second switching means and for retarding said rotary phaseshifting device, means for opening said second switching means andclosing the first mentioned switching means, and means for advancinggradually said rotary phase shifting device to increase gradually thecurrent conducted by said electric valve means.

YOSHIAKI TODA.

